The present invention relates to an optical pickup apparatus, which records and/or reproduces information on a disk and in which a plurality of laser beam sources to emit laser beams are supported on a pickup housing. More specifically, the present invention relates to a cooling mechanism for the optical pickup apparatus.
Common optical pickup apparatuses comprise laser beam sources to emit laser beams, optical parts to branch laser beams from the laser beam sources and to condense laser beams on optical disks, and an optical detector to receive reflected laser beams from the optical disks. When a signal is detected in an optical pickup apparatus, positions, in which the laser beam sources, the optical parts, and the optical detector are fixed, are important. In order to exactly perform recording and reproducing operations, it is necessary to perform adjustment to such fixed positions with accuracy.
Optical disks include CDs and DVDs, which are different from each other in wavelength of using laser beams and it has been desired that one optical pickup apparatus can use the both optical disks. Therefore, there is a need for an increase in degree of freedom of respective parts in directions of adjustment in addition to accuracies, with which laser beam sources, an optical detector, and optical parts are adjusted to fixed positions. Further, a laser driving circuit, a high-frequency module, an optical detector, a driving coil used in an objective lens driving device, etc. are also mounted on the optical pickup apparatus as parts, which generate heat at the time of recording/reproduction, in addition to laser beam sources. In this manner, many heat generating parts are mounted on optical pickup apparatuses, so that temperature rises due to generation of heat from such heat generating parts.
In particular, with a recording type optical pickup apparatus for recording of information on a disk such as DVD-RAM/R/RW, CD-R/RW, etc., much heat is generated from laser beam sources provided in the optical pickup apparatus and a laser driving circuit for driving of the laser beam sources. Further, the higher the recording speed, the more necessary high-output laser beam sources, and it is required that the laser beam sources and a laser driving circuit be arranged close to each other. On the other hand, optical pickup apparatuses tend to be made small-sized and thin. Therefore, generation of heat is liable to cause parts to undergo degradation in performance, deterioration in service life, malfunction, or the like.
In order to cope with such problems caused by generation of heat, for example, JP-A-2002-304758 discloses an optical pickup apparatus including a laser driving circuit arranged in the vicinity of laser beam sources to generate heat, the optical pickup apparatus being constructed such that a surface of the laser driving circuit opposed to a surface thereof facing a flexible substrate is put into close contact with and thermally connected with an optical pickup housing so as to dissipate heat generated from electronic parts to the optical pickup housing. With such optical pickup apparatus, it is insisted that it is possible to reduce heat resistance between the laser driving circuit arranged in the vicinity of the laser beam sources and the optical pickup housing and to effectively dissipate the heat generated from the laser driving circuit to the optical pickup housing.
Also, JP-A-2002-252408 discloses a construction, in which a heat sink is mounted on a housing, a side of a laser driver opposed to that surface thereof, to which a flexible substrate is connected, is brought into close contact with the heat sink, the heat sink is installed below the laser driver, and the flexible substrate is arranged above the laser driver.
However, with the respective conventional techniques described above, an object, to which heat generated from laser beam sources and a laser driving circuit is to be conducted, is an optical pickup housing. Therefore, in the case where both the laser beam sources and the laser driving circuit are close to each other, heat generated from the laser driving circuit is conducted to the laser beam sources through the optical pickup housing to have a possible influence on the performance and service life of the laser beam sources.
Also, in order that an optical pickup apparatus exactly perform recording/reproduction for a plurality of types of optical disks, it is necessary to adjust and position laser beam sources, an optical detector, and optical parts, respectively, in plural directions of translation and rotation. Therefore, the respective parts are not necessarily fixed to an optical pickup housing in a state of contact with the same but fixed thereto by an adhesive with a distance of several hundreds of μm to several mm therefrom. In particular, in the case where laser beam sources are connected to an optical pickup housing only by means of a small member, such as adhesive, having a coefficient of thermal conductivity of less than 1.0 W/m/K, there is a possibility that the laser beam sources becomes high temperature to have an influence on the performance and service life of the laser beam sources.